Use trigger to select values in one field based on values in another

[#1]

Hi community,  You guys are great and I really appreciate all your help!  If I have a field that has 12 values say A, B, C and woul like each of those to trigger the selection of a different value say 1, 2, 3, how would I do that?  I think I'd need to use a trigger.  I'd like something like selecting A in field ONE to select 1 in field TWO and selecting B in field ONE to select 2 in field TWO.

[AlexChirkin]

Hi, Oscar! Thank you for your answers!

Is it possible to do the same,  but with multiple selection in table F1 which will give us multiple selection in table F2 as result?